DENVER — When a Colorado emergency room nurse fell gravely ill after treating a gas-field worker, doctors struggled to figure out what was wrong with her.

Her liver, heart and lungs were failing, likely a result of inhaling ZetaFlow — a substance used in natural gas drilling — from the patient's boots. But doctors could find little treatment information in the medical texts or on the Internet because the fluid's formulation is a closely guarded trade secret.

"Nobody knew exactly where to go," said nurse Cathy Behr, 56, who since has recovered.

New regulations adopted in December to govern Colorado's booming oil and gas industry aim to make future incidents easier to handle by, among other things, requiring companies to disclose to doctors and emergency workers the ingredients they use.

Regarded as the most comprehensive in the country, the rules have been hailed by some as providing much-needed protections for the wildlife and environment but assailed by others as punitive — and potentially crippling — for an industry critical to Colorado's economy.

"We think these are the right regulations for Colorado," said Dave Neslin, acting director of the state's Oil and Gas Conservation Commission. "The oil and gas industry ... has a large footprint within the state. We think these rules strike an appropriate and sustainable balance." The requirements come as Colorado is struggling to keep pace with a significant energy boom. A decade ago, state officials issued 1,000 drilling permits per year; in 2008, they are on pace to issue more than 7,600, Neslin said.

The regulations:

• Create a 300-foot-wide protection zone around streams that provide drinking water.

• Require operators to disclose information about their chemicals to emergency responders and physicians, although the information may not be released publicly.

• Require emission controls on operations within a quarter-mile of schools and homes in northwestern Colorado.

• Allow state health and wildlife officials to review applications for operations that could affect public health or wildlife habitat.

The Colorado Oil and Gas Association, an industry trade group, regards that last rule as particularly onerous.

"As a result ... this process becomes the most burdensome in the nation," said John Swartout, vice president of government and legislative affairs for the association.

Swartout said it already takes longer to apply for a permit in Colorado than in other gas- and oil-producing states — an average of 65 days, compared with two to seven days in other states.